[Mesa-dev] [PATCH] include: Add helper header to help trap includes inside extern C.

[Jason Ekstrand]

On May 13, 2015 8:01 AM, "kallisti5" <kallisti5 at unixzen.com> wrote:
>
> On 2014-12-11 16:14, Jose Fonseca wrote:
>>
>> From: José Fonseca <jfonseca at vmware.com>
>>
>> This is just to help repro and fixing these issues with any C++ compiler
--
>>
>> commiting this will of course wait until all issues are addressed.
>>
>>
>> $ scons src/glsl/
>> scons: Reading SConscript files ...
>> Checking for GCC ...  yes
>> Checking for Clang ...  no
>> Checking for X11 (x11 xext xdamage xfixes glproto >= 1.4.13)... yes
>> Checking for XCB (x11-xcb xcb-glx >= 1.8.1 xcb-dri2 >= 1.8)... yes
>> Checking for XF86VIDMODE (xxf86vm)... yes
>> Checking for DRM (libdrm >= 2.4.38)... yes
>> Checking for UDEV (libudev >= 151)... yes
>> warning: LLVM disabled: not building llvmpipe
>> scons: done reading SConscript files.
>> scons: Building targets ...
>> scons: building associated VariantDir targets:
build/linux-x86_64-debug/glsl
>>   Compiling src/glsl/ast_array_index.cpp ...
>>   Compiling src/glsl/ast_expr.cpp ...
>>   Compiling src/glsl/ast_function.cpp ...
>>   Compiling src/glsl/ast_to_hir.cpp ...
>>   Compiling src/glsl/ast_type.cpp ...
>>   Compiling src/glsl/builtin_functions.cpp ...
>> In file included from include/c99_compat.h:28:0,
>>                  from src/mapi/u_compiler.h:4,
>>                  from src/mapi/u_thread.h:47,
>>                  from src/mapi/glapi/glapi.h:47,
>>                  from src/mesa/main/mtypes.h:42,
>>                  from src/mesa/main/errors.h:47,
>>                  from src/mesa/main/imports.h:41,
>>                  from src/mesa/main/core.h:44,
>>                  from src/glsl/builtin_functions.cpp:58:
>> include/no_extern_c.h:48:1: error: template with C linkage
>>  template<class T> class _IncludeInsideExternCNotPortable;
>>  ^
>
>
> Good morning,
>
> This change breaks all of the Haiku code as we use a *lot* of C++ code
inside
> of Mesa (well, all the OS interfaces are C++ that wrap the Mesa C)
>
> /Builds/mesa> find . -name "*.cpp" | grep haiku
> ./src/egl/drivers/haiku/egl_haiku.cpp
> ./src/gallium/targets/haiku-softpipe/GalliumContext.cpp
> ./src/gallium/targets/haiku-softpipe/SoftwareRenderer.cpp
> ./src/mesa/drivers/haiku/swrast/SoftwareRast.cpp
>
>
> Example:
>   Compiling src/util/u_atomic_test.c ...
>
> In file included from include/c99_compat.h:28:0,
>                  from include/c11/threads.h:38,
>                  from src/mesa/main/mtypes.h:39,
>                  from src/mesa/main/errors.h:42,
>                  from src/mesa/main/imports.h:44,
>                  from src/mesa/main/context.h:52,
>                  from src/mesa/drivers/haiku/swrast/SoftwareRast.h:20,
>                  from src/mesa/drivers/haiku/swrast/SoftwareRast.cpp:14:
> include/no_extern_c.h:47:1: error: template with C linkage
>
>  template<class T> class _IncludeInsideExternCNotPortable;
>  ^
> In file included from include/c99_compat.h:28:0,
>                  from src/gallium/include/pipe/p_compiler.h:32,
>                  from src/gallium/auxiliary/util/u_math.h:42,
>                  from src/mesa/main/macros.h:35,
>                  from src/mesa/main/colormac.h:37,
>                  from src/mesa/drivers/haiku/swrast/SoftwareRast.cpp:28:
> include/no_extern_c.h:47:1: error: template with C linkage
>
>  template<class T> class _IncludeInsideExternCNotPortable;
>
> Any alternative fix ideas besides me adding a if !defined(__HAIKU__) to
include/no_extern_c.h?

Please do not do that!  The whole point of this patch is to catch places
where headers are included inside an extern "C" block.  This patch makes
them a compile error instead of being silently wrong.

The correct solution is to fix the haiku platform integration so it doesn't
do this.

--Jason

>  -- Alex
>
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